Automatic switching system applicable to telegraphy



H. L. LESIGNE 2,673,234

ll Sheets-Sheet 2 March 23, 1954 AUTOMATIC SWITCHING SYSTEM APPLICABLE TO TELEGRAP Original Filed March 16, 1946 March 23, 1954 H. LESIGNE AUTOMATIC SWITCHING SYSTEM APPLICABLE TO TELEGRAPHY l1 Sheets-Sheet 3 Original Filed March 16, 1946 lll/L TIPLED FIG 4A 5% DLS BM 2 TO H6275 JIVVENTOE/ a Hs'me lav/.5 [616 ME M )M flrraemfyi d manna aoauonmo March 23, 1954 H. LESIGNE AUTOMATIC SWITCHING SYSTEM APPLICABLE TO TELEGRAPHY Original Filed March 16, 1946 ll Sheets-Sheet 4 luvewran /lemer 001.: Zea/61v:

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H. L. LESIGNE 2,673,234

AUTOMATIC SWITCHING SYSTEM APPLICABLE TO TELEGRAPHY ll Sheets-Sheet l0 flrrokweys H. L. LESIGNE March 23, 1954 AUTOMATIC SWITCHING SYSTEM APPLICABLE TO TELEGRAPHY ll Sheets-Sheet 11 Original Filed March 16, 1946 Ivvavran HENRI 1001a Les/E E M *6;

flrraRNYJ Patented Mar. 23, 1954 UNITED STATE.

AUTOMATIC SWITCHING SYSTEM APPLI- CABLE TO TELEGRAPHY Henri Louis Lesigne, Vanves (Seine),

France, as-

signor to Compagnie Gcnerale dElectricite, Paris, France, a corporation of France Original application March 16, 1946, Serial No.

654,845, now Patent No. 2,529,166, dated November 7, 1950. Divided and October 11, 1950, Serial March 31, 1953 this application No. 189,547. In France Section 1, Public Law 690, August 8, 1946 Patent expires March 31, 1963 14 Claims.

This application is a division of my U. S. Patent No. 2,529,166, dated November 7, 1950.

The present invention relates to automatic switching systems more particularly applicable to telegraphy.

It relates, especially, to that kind of automatic switching which is the subject of my British specification No. 668,261.

In telegraphic systems, the supervision relays arranged in series or in shunt on the wires of the line are generally polarised permanent magnetic relays which present the inconvenience of being expensive and require delicate regulating.

The present invention replaces these polarised permanent magnet relays by more economical and stable relays with a shunted magnetic field. These relays have the quality of attracting their armature when the two coils are traversed by a current of the same sense. They fallback when the currents are of an opposite sense. These relays are used in the equipment of telegraph stations in equipment known as a Connection Circuit or Link Circuit and in the device known as a Recorder or a Register.

Furthermore, the call-relay employed is a nonpolarised relay with a magnet or electromagnet which permits discrimination of the direction of current through th line, the control of the passage of current through that line, and operation only in a determined direction.

One of the functions of the recorder is also to discriminate between stations according to their category. In the first category no charge is effected, whereas in the second category, a charge must be made. The recorder then sends the signals necessary for determining that charge.

These signals are sent either locally, if the calling station is connected to the local automatic switch (this word here designating the switching office or station), or over the line to the calling station, if this is connected to another automatic switch. The signals sent locally to the recorder Which prints the duration of the communication indicates: the number of the called station, whether the called station has been found free or occupied, or whether the calling station is connected to overflow equipment, and to which overflow equipment the calling station. is connected. If the calling station is not connected to the automatic switch of the calling station, impulses are sent over the line to a remote automatic switch appropriated to the station of the calling subscriber. The number of the impulses sent varies according as the station of the called subscriber has beenfound free or occupied, or

the calling subscriber is connected to overflow equipment. In the last case, the number of impulses sent varies according as the overflow relates to the first, second or third figure (or digit), thereby indicating also to the printing recorder in which stage of selection the overflow has occurred.

The recorder also permits the sending of a characteristic signal if the required station is occupied.

The present invention also envisages the possibility of indicating to the recorder that an operation is to be effected in a stage of selection, or to pass on from that stage of selection without the necessity of eifecting a translation of the figures received in the recorder.

Furthermore it permits the changing of the route of a communication when the direction which it should ordinarily take is occupied. Nevertheless, the change of route cannot take place for communications which come from certain directions.

The present invention also comprises a device called a Discriminating Recorder, the purpose of which is to replace the recorder in automatic switches when there is little local trafiic, and when the traffic is in great measure shunted to another ofiice. This device fulfills the same functions as the recorder in the establishment of local communications.

The invention permits the substitution, in an automatic switch, for a recorder (that is, a device which permits the reception and the retransmission of the figures received in transit without it being necessary that the selector or connector should be connected to an outgoing line), of a discriminating recorder, that is, a simple device, placed in series or in shunt with the line, and which determines whether the communication is local or in transit. This change may be effected without alteration of the cables. The recorder and the discriminating recorder being mounted on interchangeable flanges.

The present invention also provides for a recorder for charged communications, the purpose of which is to receive the impulses which determine the called station, to search by means of one or two seekers also called finders, according to the importance of the office, for the number of the calling station, and to receive impulses indicating the development of the communication: for example, requested station free, requested station engaged, transmission to over flow equipment in a local automatic switch, trans- 3 mission to overflow equipment, whether at the first, second or third selection. It retransmits these impulses to a. group of devices called a printing recorder. It controls the placing in position of various elements provided with wheels with printing characters which form this group. It controls the printing, on a band of paper, of the calling and called numbers, or of the place at which overflow occurs and the time when the communication begins.

The task of the recorder for charged communications is, furthermore, to search for the calling stations by a testing circuit provided at each station or at each finder.

The present invention relates equally to a printing recorder which comprises a very restricted number of elements and which is controlled by the recorder of the charged communications and remains connected to the connection circuit during the whole duration of the communication.

It comprises the following:

Electromagnets provided with wheels with printing characters which determine first the number of the called station, then with the same elements the number of the calling station, these being transmitted to it by the recorder of charged communications.

An 'electromagnet for printing the calling and called stations.

An electromagnet provided with a wheel with printing characters which indicate the development of the communication, that is, which show whether the called station is free or engaged, or whether it has been retransmitted to overflow equipment, and, in that case, whether overflow has occurred at the first, second or third stage of selection.

An electromagnet for pringing the communication.

An electromagnet controlled by time-mechanism for indicating the time.

An electromagnet for printing the time.

An electromagnet for advancing the band.

It comprises, furthermore, four relays for the establishment of the connection between the recorder and the connection circuit, for the release of the electromagnets, and for recording the time at which the communication has ended.

the position of The present invention afiords the possibility of increasing the number of lines connected to an automatic switch without increasing the number of the figures which serve to effect the selection. Several lines may 'be assigned to the same calling number, but the number of figures which may be thus assigned need not be diminished.

According to a particular feature of the invention, one and the same selection figure may serve for two successive stages without retransmission of that figure, since the numerical elements, also called digit switches, of the recorder which orient the selection elements may be used once or more.

In the second instance, the invention permits the orientation of a selector in a given direction by making use of different figures, these figures being able to control the different directions at the succeeding stage of selection.

These various features of the invention and also others will appear and be better understood by a perusal of the following description which relates to an application of the system and is given by way of example and by reference to the drawings attached to the text.

Fig. 1 is a schematic arrangement of elements entering into communication in the case where a recorder and a call finder are employed.

Fig. 1a is an assembly diagram showing how Figures 2, 3, 4, 5, 6, 7, 8, fit with relation to each other.

Figs. 2, 3, 4a, 4b, 5a and 5b, 6 and 7, are detailed complementary schematic drawings and are related according to the sketch of Fig. 1.

Fig. 2 represents a control box for a telegraph station.

Fig. 3 shows the two special relays at each station, the input of the line to the automatic switch, the equipment of the call finder, the equipment of the connection circuit with the finder of the connection circuit and the first selector and the equipment of the connector.

Figs. 4a, 4b, 5a and 7b illustrate a recorder.

Fig. 6 illustrates a supply element operated by rectified current and allotted to each recorder. This element has been described in the above mentioned British specification N 0. 668,261.

Fig. 8 illustrates a recorder for printing the duration of a communication.

Figures 7a and 7b show a recorder for charged. "i communications.

Figures 9a and9b show a discriminating recorder.

Fig. 10 illustrates the connection of control wires when a secondary connector is employed.

Figs. 11 and 12 illustrate a device for changing the route of a communication.

The group of elements which enter into the establishment of a communication asshown in Fig. 1, consists essentially of the control-box of a calling station P, of its line equipment (call and metering relay) R, starting relays G, the recorder A with the finder of the recorder XI, of a connection circuit B with the finder of the connection circuit X2, or of a connection circuit B with its finder X4.

The connection circuit B is exclusively appropriated to an element relating to a figure in the hundreds. It is metallically connected to a call finder X4 fitted to the element in question.

The group of elements entering into the establishment of a communication comprises furthermore:

A call finder DX4.

A first selector with its rotary switch X3.

The group of primary selectors X3 is connected to the group of recorders A by control wires Cl.

A connector lil with its rotary switch X5.

The group of selectors or connectors is connected to the group of recorders A by control wires C3 and C4.

The line equipment of the called station R.

A control box of the called station P.

A recorder for charged communications H with its finders: that of the recorder X1, that of the printing recorder X8, and the finders of the calling station X9 and Xi 0. I

A printing recorder I with its finder XH.

The illustrated installation is for three selec-.

tions. For four selections there should be anadditional selector. For six figures two further selectors etc., but for two figures there would be no first selector.

The function of the system is in its broad lines as follows:

The operator of the calling station pushes down a call button but does not disconnect the control box of the station. He thereby excites the line relay of the station which operates the starting relays, these in turn closing the starting,

The recorder Ctr of the calling station. Whilst the operations of preselection of the calling subscriber are being effected, a recorder for charged communications searches for a recorder and is temporarily connected theretol It then searches for a printing recorder which in its turn searches for the connection circuit with which the assembly of a recorder and a recorder'for charged communications is connected. A stand-by current is then sent'overa wire of the calling station. The reception of this current at the calling station effects: starting up of the motor connection of the telegraphline with the teleprinter through the control box. The operator then releases the call'button of the control box, and dials the number of the called station, which may consist of three figures, as follows:

The first figure is received in the recorder by numerical element allotted to thousands. The first selector is oriented, by means of the control wires on the corresponding network to the same position as the numerical element allotted to of the teleprinter,

thousands, then it searches for a free connector in the group in question. The second and third figures are received by numerical elements respectively allotted to tens and units, and orient the connector on the called line.

The various selections are similarly received by the recorder for charged communications, which orients electromagnets of the printing recorder these being providedv with wheels and printing characters and which prints the number of the called station on a band of paper.

In the meantime, the recorder for charged communications has searched the calling line and is cognizant of the number of the caller by the azimuthal position of its hundreds and subscribers finders. It orients the electromagnets of the printing recorder which are provided with printing characters and prints the number of the calling station. If the called station is free, it is called up by transmission of current of positive polarity over one of the wires of the line.

Reception of positive current at the controlbox of the called station starts the motor of the teleprinter associated with that station, and connects the telegraph line with that teleprinter.

A characteristic signal i then transmitted by the recorder to the called station. Reception of this signal stops the transmission by the called station of the indicative signal of that station which is sent out tothe calling station and received by the recorder also. The recorder then transmits the same characteristic signal to the calling station, and thereupon establishes a connection in the connection circuit the two telegraph lines being by this means connected With each other.

The .recorder forl charged communications then records on the printing recorder the time when the communication begins.

Then the recorder. and the recorder for charged communications are released, leaving the printing recorder connected to the connection' circuit during the whole duration of the communication. Upon the release of the elements at the end of the communication, the printing recorder marks the time when the communication ends, and is thereupon released.

the bank of the In the detailed description which follows the letter 1' preceding the number of a contact spring of a relay indicates the contact established by the spring when the relay is at rest (not excited) and the letter t the contact established by this spring when the relay is at work. In this specification, the same relay and its contacts may be designated in any one of three different manners, according to its being considered independently of its condition of energization or, de-energization, or considered to be in an energized condition or in a de-energized condition. Thedesignation of the relay in the first case will include neither the letter it nor the letter 1*, but, in the latter two cases will include either the letter if or the letter r.

It may be assumed, for instance, that a station wants to reach another station, the number of which is 25681. Referring now to Fig. 2, the operator at the calling station presses down the call button P of the control-box of the station. C is the dial of the calling subscribers station.

The pressing down of this button places a positive polarity (a stand-by telegraphic) on wire I of the station and starts the relay of line A (Fig. 3) by means of the following connections:

(Fig. 2), the positive resistance of the battery, the working contact of button P which is kept locked, T22 and wire I.

(Fig. 3), the winding RC3 of relay A, the rectifier Ar operating in current, and ground.

Relay A attracts armature and closes the circuit of the starting relay Ml as follows:

Ground, tAZ, the winding of MI and the battery.

Relay MI sets a distributor (not shown on the.

drawing) in operation, by means of the following connections Ground, M I2, rTI and point 1.

The ground connection is cut off as soon as relay T is excited, by means of the following connections:

Ground, tMIZ, the battery.

The entry into action of relay Ml a test circuit on the call finders which have access to the group of which the calling station is a part, as follows:

Ground, MI I,

winding of relay T and the finder of explored by the brush T.

On the other hand, relay MO is grounded, and

the following connections are established:

Ground, TMZI, r026, the resistance, the wind the connection circuit m r oz and the battery.

Relay M02 is common to all call finders of the same group. It prepares the operational circuit of-relay MCi. Relay MCI is common to all connection circuits explored by the same recorder. The plug M which is common to all the connection circuits which have access by their finders to the call finders of a group in which a subscriber is being called, is brought to positive polarity thereby indicating a free line by means of the following connections:

-Ground, tMCZl, the resistance, HI, and plug M- on the bank of recorders.

The traffic distributor, by means of connections the same direction as the establishes 1'M2I, the resistance T023, and

4) then enters Ground; MCI2 (Fig. 3')", point II (Fig; 4) .point 25, the coil in the trafiic distributor which is not shown in the drawing, point 26, sector A of switch X5 in its rest position, sector A in, rest position of switches XI,- X2, X3and X4, wire 62 (Fig. 5) sector C in rest position of switch XI, contactG of the mixer (sequence switch) X6 in position 0, wire 53 (Fig. 4), the winding of relay 9 and the battery.

By'means of contact 1:92, relay 9 is held independently of the tralfic distributor which has efiected its attraction, as follows:

Ground, tMCiZ (Fig. 3), point II (Fig. 4), t92, the rest position of numerical elements X5, XI, X2, X3 and X4, wire 52 (Fig. 5), sector C of X1 in its rest position, contact G of the mixer X6 in its rest position, wire 58 (Fig. 4), the winding of relay 3 and the battery.

As long as the relay M 10 (Fig. 3) is working, that is as long as the call continues which brings a connection circuit on the bank of arecorder into action, relay 9 is attracted (see Fig. 4). It returns to rest either because the recorder of which it forms part, establishes connection with the calling station, or because another recorder is connected to the calling station, and thus blocks the operation of the recorders.

Relay 9, when in operation, effects the excitation of relay I3 by means of the following connections:

Ground, 2395, wire 42 (Fig. 5), contact C of mixer X6 in position 0, the lower winding of relay i3 and the battery. 7

Rotary switch E begins to rotate automatically and searches for a connection circuit in which plug M has positive polarity. Its rotation circuit is closed, as follows:

(Fig. 4), battery, tBI, wire 31 (Fig. 5), TIM, H34, contact A of mixer X6 in rest position, wire 35 (Fig. 4), TH, rlfll, the interrupter,- the wind ing of E and the battery.

Therotation circuit of switch E is opened, upon the closing of the blocking circuit, at the time when brush M passes a contact corresponding to a connection circuit which has access to the called group. Relay M is excited by means of the following connections:

(Fig. 3), ground, tMCZI, the resistance RZI', contact M brush M (Fig. 4), L93, r102, rlll', wire M (Fig. 5), contact C of mixer XI in position 0, the winding of relay I4 and the battery.

By means of contact TIM, the rotation of E is interrupted. On the establishment of contact Hi I, relay as connects the upper winding of relay I3 to the battery, wire 31 (Fig. 4), HI and the battery. The other end'of its winding is connected to wire E, and current flows through the two windings of relay I3. The relay I3, the two windings of which are arranged differentially, falls back when the flux produced by the upper winding cancels the flux produced by the lower winding. This condition is fulfilled if none of the other relays I3 is connected to the same point E.

On the other hand, the upper winding of the relay I3, which is a low resistance winding, shunts the winding of relay It. The potential of test plug E consequently falls to a value near the potential of the negative pole of the battery. The connection circuit is thus protected against engagement by another recorder. Relay I3 at rest and relay It in operation characterise the engagement of an unoccupied element.

In the opposite case, relay It falls back, these relays being designed in such a manner that two of the relays I4 are not able to operate simultaneously, since each is shunted by thewindmg; of relay I3.

Excitation of relay I4' and de-energization of relay I3 efiect the attraction of relay I6- asfollows:

The battery, resistances 1'I3I, H42, the-winding; of relay I6 and ground.

Bymeans of the following circuit: ground, rIlI, H63, contact D of mixer X6 in position 0', wire 43 (Fig. 4) and Hill, the energising circuitof relays II! and I0 is closed, their lower windings being arranged in series. Relay I0, the attraction of which is delayed, will not yet have attracted its armature when the contacts of relay Ill are already established. By means of contact H82, the upper windings of relays I0 and II) are connected in branch with point M. Relay ID held by its upper winding, but relay ID, the windings of which are arranged differentially cannot operate, and its relays II) and II! are connected by contact H02- in shunt to the group formed by relays I3 and I4. Relay I4 being shunted, relay I3 functions again, and opens the circuit of relay I'E which then falls back. The grounding of the lower windings of In and Ill effected by contact H63, is interrupted. Relay I0 attracts its armature. The two relays- Ill andv Iii are held in working position by means of the following connections: 7

The upper windings of II) and I0, tIIlZ, t9'3, brush M, contact M (Fig. 3), 12I, resistance tMC2I and'ground.

The rotation circuit of the finder in the connection circuit is thus closed, as follows:

(Fig. 4) the battery, tQI, wire 31 (Fig. 5) TIM,

H34, contact A of mixer X6 in position 0, wire 35 (Fig. 4), H1, H03, TII3, brush RI of the finder of the connection circuit, contact RI (Fig. 3), the interrupter, the winding of the electromagnet RC1 and ground.

Rotary switch RCI participates in the search for a free finder which has access to the called line, on the passage ofv brush T over a free call finder characterised by the positive battery on plug M. Relay I4 of the recorder (Fig. 5) is energised by means of the following connections:

(Fig. 5), the battery, the Winding of relay Il, contact 6 of mixer X6 in position 0, wire 4| (Fig. 4), NH, H02, 1594, T13, brush TI of the finder of the connection circuit, contact TI (Fig. 3), the brush and bank T of the finder of the connection circuit rC23, resistance rMZI, tMII and ground. 7

Relay I4 of the recorder (Fig. 5) then comes into operation. By means of contact TIM, it opens the rotation circuit of the finder of the connection circuit. Armature I4I of relay I4 shunts the upper winding of relay I3, which is a low resistance winding, across the winding of relay I4. The potential of the test plug consequently falls to a value near the potential of the negative pole of thebattery. The call finder is thus protected against engagement by another connection circuit.

Relay I 3, which is a, differential relay, falls back, because the fluxes which, its two windings produce balancev each other exactly.

Relay I3 at rest and relay I4 in operation close the attraction circuit of the relay It by the following connections:

The battery, resistance, rI3I, H42, the winding of relay Ifi and ground.

They also close the attraction circuit of relay II by the following connections:

Ground. 1-I'II, H63. contact D of mixer X3 in,

armature is left at rest. But

tact T of the back of of the. recorder then functions by means of the contact 6 of mixer X6 in position 0, wire 43', tIIlI, rI I3, the lower windings of relays I I and I I and the battery.

Relays II and II operate in the same way as relays Ill and I 3'. Relays I3 and I4 are shunted by the windings of relays II and II. Relay i3 is again excited and opens the attraction circuit of relay I6 which therefore falls back. Relay I I, the lower winding of which is isolated from ground by means of contact H63 then begins to operate under the influence of its upper winding. Relay 8 then functions by means of connections:

The battery, the two windings of relay 8 in series tI I I, brush SI of the finder of the recorder, contact SI (Fig. 3), the brush and bank S of the finder of the connection circuit, rCi i, the

winding of relay C2 and ground.

Relay C2 cannot begin to operate, because the resistance of the two windings of relay 6 is too great to permit of its functioning. Relay 6 of the recorder therefore closes the rotation circuit of the call finder RC2 as follows:

(Fig. 4), the battery, till, wire 3'! (Fig. rI4I,.ti34, contact A of mixer X6 in position 0, wire (Fig. 4.), H71, H83, tIIZ, t33, brush B! of the finder of the recorder, contact B'I (Fig. 3), the brush and bank 33 of the finder of the connection circuit, r022, the interrupter, the winding of RC2 and ground.

The call finder RC2 begins to rotate automatically when exploration of the calling line starts. This line is characterised by a polarity which may be called a blocking polarity on conthe call finder. Relay I4 following connections:

(Fig. 5), the battery, the winding of relay I4, position 0, wire 4! (Fig.

4), HM, t82, rZiiI, rll2, brush AI of the finder of the recorder, contact A! (Fig. 3) the brush and bank A of the finder of the connection circuit, rCZI, brush T of the call finder, and contact T which corresponds to the called line 'I.

"The rotation circuit of the call finder is opened by means of contact HM, and blade I 4| of relay I A shunts the upper winding of relay I3, which is a low resistance, across the winding of relay !4. The potential of plug T of the calling line consequently falls to a value near the potential of the negative pole of the battery. The called line is thus protected against engagement by another connection circuit.

Relay It, which is a differential relay, falls i back, because the flux produced by its two winding, balance exactly.

Relay I 3 at rest and the relay I4 in operation close the attraction circuit of relay I6 via:

(Fig. 5), the battery, resistance rI3I, M42, the

V winding of relay I6 and the battery.

The circuit of relay 3 of the recorder (Fig. 4)

is then closed via:

Left hand coil, ground, t9I', the winding and the battery.

Right hand coil, the positive current, the resistance tII4', wire (Fig. 5), H62, wire 44 (Fig. 4), t8l, the right hand winding and ground.

Relay3 which is a relay with a shunted magnetic field, and the windings of which are traversed by current ofany desired direction,

comes into operation.

battery.

.70 Operation of relay 3 effects attraction of relay the recorder since Relay 4 closes a holding circuit by means of contact 2544, and contact t42 establishes the circuit of the left hand coil of relay 3, which is open at tSI as soon as relay 9 is released at the end of the preselection operation.

By means of contact t lt, it excites relay 7, which connects the recorder of the callin line.

By means of contact till (Fig. l), relay 1 engages the connection circuit with wiper M. A battery in series with a resistance is connected to wire TI to hold the connection relays by means of contact tit. By means of contact tie, relay I short-circuits the upper winding of relay 8. Relay 02 (Fig. 3) of the call finder, in serie with rela s, then begins to operate, and by means of its working contacts it establishes the connection of the calling station with the recorder by means of the following connections:

(Fig. 4.), ground, the right hand winding of relay 3, t'IS', wiper B of the finder of the recorder, contact B (Fig. 3) rZI, the brush and bank B of the finder of the connection circuit :022, the brush and bank 13 of the call finder, wire B, point I (Fig. 2), r22, the working contact of button P, the resistance and positive pole.

Relay 3 of the recorder (Fig. 4) is held in operation. Relay I t of the recorder having had its circuit open at rCZI (Fig. 3) falls back, and at H42 (Fig. 5) it opens the attraction circuit of relay I6 which also falls back, thereby opening at H62 the attraction circuit of relay 3 which remains under the effective control of the calling station, this being a station for charged communications. Relay 1 of the recorder begins to operate by means of the following connections:

(Fig. 6), the secondary of transformer TFI, the rectifier RDI, RDZ in the same direction as the current, point 23 (Fig. 4), 2612', i912, rIII', brush SI of th finder of the recorder, contact S2 (Fig. 3), brush Sand bank S of the finder of the connection circuit tC'24, the brush and bank S of the call finder, the resistance, point I), point tID (Fig. 4), TIM, the lower winding of relay I, the rectifier RDI in the same direction as the current, t94, 1612, point 24 (Fig. 6), either rectifier Rd3 or Rd4 and the secondary of the transformer.

Relay I begins to operate and closes its holding current by means of the following connections:

Ground, t'II, the upper winding of relay I and the battery.

Thus relay I puts the recorder for charged communications (Fig. 7) into operation by means of the following connections:

(Fig. 4 ground, tI3, th resistance, point I220. (Fig. '7), r83, contact b of the mixer XI in position 0, the winding of relay 2 and the battery.

Relay 2 closes the circuit of the differential relay 3 which begins to operate by means of the following connections:

Ground, t2I, contact d of mixer XI in position 0, the lower winding of 3 and the battery.

The circuit of the switch RC is then closed as follows:

The battery, MI, t33, t23, the contact-breaker, the winding of CE and ground.

The switch CE participates in exploration of it is connected with a connection circuit which is itself in connection with the called line. This recorder is characterisedby a positive polarity on its wire M (Fig. 4), ground, tI I3, theresistance, and bank M. When the wiper M of the finder CE passes over the contact M which corresponds to this recorder, relay I i of amaze;

bank of CE (Fig. 4), the resistance, tie and ground, and it closes a holding circuit by means of its element 1543.

The rotation circuit of finder CE is open at MI (Fig. '7). By its blade II, relay 3 places the upper winding of relay 3 which is of weak resistance in shunt with the winding of relay 4. The

' potential of the plug consequently falls to a value near the potential of the negative pole or the battery.

The recorder is thus protected against engagement by another recorder for charged communications.

I balance exactly.

Relay I (Fig. 7) then begins to operate by means of the following connections:

Ground, r3I, m2, contact a of mixer XI in position 0, the lower winding of Iii and the battery and it closes a holding circuit by means of H 04, the wiper and bank M of finder CE (Fig. 4) the resistance, tI3 and ground.

Relay 3 then begins to operate by means of the followin connections:

Ground, tIIl2, the winding of 8 and the battery.

The circuit of the electromagnet oi mixer XI is closed as follows:

Ground, us, contact 0 of mixer XI in position 0, the winding of Xi and the battery. Mixer XI then attracts its armature.

On the other hand, the attraction circuit of relay 2 is opened at 1'33, and relay 2 which has a release, overcomes its delay and falls back, thereby opening at t24 the attraction circuit of switch 7 XI which then releases its armature and brings its brushes into position 1.

Relay 3 operates under the action of its lower winding the circuit of which is again closed as follows The battery, the lower winding of relay 3, contact d in position 1 of XI, tSII and ground.

printing recorder then begins, REI is closed on the contact T of the bank of the finder REI as follows:

Ground, the winding in parallel of relay I, r2I, rI4I, and contact T.

When the Wiper T of the finder REI passes over the contact T which corresponds to a free printing recorder, relay d of the recorder for charged communications begins to operate by means of the following connections:

The battery, the winding of the relay 4, 1232, contact 19 of mixer XI in position 1, wiper T (Fig. 8), contact '1, TIM, r2I, the two windings I of relay I and ground, and it closes a holding circuit at T43.

The rotation circuit of switch REI is open at By means of its blade GI relay 4 places the upper windin of relay 3 (which is a winding of weak resistance), in shunt with the winding of relay 4. The potential of the test plug consei2 quently falls to a value near the potential of the negative pole of the battery.

The printing recorder is thus protected against engagement by another recorder for charged communications.

Relay 3, which is a differential relay, then falls back, because the fiux produced by its windings is exactly balanced.

Relay 3 at rest and relay 4 in operation in position 1 characterise the end of exploration for a free printing recorder. Mixer X! has its circuit closed as follows:

Ground, r3I, hi2, contact 0 of mixer XI in position 1, the circuit-breaker, the winding of XI and the battery.

Mixer XI then brings its wipers into position 2. In this position exploration for connection circuits in engagement with the calling line and the recorder is effected.

The rotation circuit for the finder of the printing recorder is closed as follows: (Fig. '7), the battery, H23, rIII, tIoI, contact 0 of mixer XI in position 2, wiper R of finder CEI, contact R of the circuit-breaker bank, the winding of R0 and ground.

Switch RC participates in the search for a connection circuit in engagement with the recorder. The connection circuit is characterised in that its wire S has a common point with Wire S of the recorder.

When wiper S of the finder of the printing recorder passes over the wire S which corresponds to a connection circuit associated with a recorder connected with the recorder for charged communications, and with which the printing recorder itself is momentarily associated, relay II of the recorder for charged communications (Fig. 7) begins to operate by means of the following connections:

(Fig. 6), the secondary of TFI, rectifier RDI or RD2 in the same direction as the current, point 23 (Fig. 4) 1512, TI I I, wiper SI of the finder of the recorder, contact SI (Fig. 3), contact S of the bank of the finder of the printing recorder, wiper S of RC (Fig. 8), contact S of the bank of the finder of the r corder for charged communications, wiper S (Fi '7), contact a of mixer XI in position 2, H95, the winding of relay II, r24, H03, wiper S of the finder of recorder CE, contact S of the bank (Fig. 4), H6, rectifier RDI in the same direction as the current, tI2, point 24 (Fig. 6), rectifier Rdi in the same direction as the current, and the secondary of transformer TFI.

Relay II, at rI II opens the rotation circuit of the finder of the printing recorder RC which stops its wipers on the designated connection circuit.

The circuit of the crossing relay is then closed as follows:

Ground, t8I, tIl2, contact 22 of mixer XI in position 2, the winding of relay I2, the resistance and the battery.

The circuit of mixer XI is closed as follows:

. Ground, tI2I, contact d of mixer XI in position 2, the circuit-breaker, the winding of XI and the battery.

Mixer XI then, brings its brushes into position 3.

Since relay I I has had it circuit open at H24, it falls back, and by means of contact tII2, it opens the circuit of relay I2, which is held in operation notwithstanding its delay. In this position the circuit of the electromagnet which adregcrsgase vances the band of the printing'recorderis closed as follows: a

(Fig. 7), ground, r84, contact a of mixer XI in position 3, wiper Ab of finder REI, contact Ab (Fig. 8), relay I3 and the battery.

Re1ayI3 advance the band. At the same time, mixer XI I having attracted its armature.

its circuit of attraction is closed asfollows:

' Groundftal; H22, contact 0 of mixer XI, the winding of the electromagnetXI and the batt'ery. "Relay I2, the circuit of which is closed via: "Ground, t8I, t22, contact 2) of mixer XI in po- ""sition 3, the winding of relay I2, m2, t8I and ground, exhausts its period of delay and falls "back, and at tI22 it opens the attraction circuit of electromagnet X! which thereupon releases its armature, and brings its wipers into position 4.

At this moment the operator of the calling station must be informed that he can compose on his dial the number of the station which he wants to reach, say: 25881.

One of the Wires of the line is then connected 'th the positive pole of the battery, due to the following connections: (Fig. '7) the positive terl minal of thebattery; the resistance, I, t85, wiper b er finder on, Contact b (Fig. 4), H I I, 1132, RI, fwire (Fig. 5), 12m, m2, wire 3| (Fig. 4),

brush A of the finder of the recorder, contact a (Fig. 3), the wiper and contact A of the finder poffthe connection circuit, tCZI, the wiper and contact A of the cal -finder, wire A, point 2 (Fig. 2, the resistances of the winding of relay I in series with the line, the winding of the telegraphic relays in series and ground.

The polarised relay 3 reciprocates its armature which comes into contactwith its positive stop.

Then the relayz begins to operate by means of the followingconnections:

The positive terminal of the battery, the resistance, the positive stop of relay 3, r23, the wind of 2 and the battery.

Relay 2 closes a holding circuit by means of contact r2l, the resistance and the positive terminal of the battery.

By means of its contact r2I, relay 2 closes the circuit of the left hand coil of relay I which has a shunted field. This relay, the two coils of which are traversed by current of the same direction, begins to operate, and at H! it opens the release circuit of relay 2. At H2 and t23, relay 6 connects the telegraphic circuit with the teleprinter across the junction-box. At 1323' and i124, relay 6 establishes a connection between the motor situated at points 5 and 6 and the supply situated at points 3 and 4. The start of the motor of the teleprinter indicates to the operator that a recorder is connected to its line.

He ceases to press down the call button of teleprinter P.

The operator then composes on the dial of the control-box the number of the called station.

Reception These impulses of double current strike relay 3 of the recorder (Fig. 4). Relay 3 is a relay with a shunted magnetic field which falls back at each 14 emission of negative current. These pulses are sent by means of the following connections:

a Negative current, the resistance, the left hand contact of the dial C (Fig. 2), 2522, wire I (Fig. 3), contact B and wiper B of the call finder, tC22, contact B and wiper B of the finder of the connection circuit 72!, contact B! of the bank of the finder of the recorder (Fig. 4), wiper BI, 1318', the right winding of relay 3 and ground.

The first release of relay 3 determines the start of the operation of relay 5 by means of the following connections:

Ground, 1'3I, Hi l, the winding of relay 5, the

resistance wound on relay 5 and the battery.

Relay 5 is short-circuited at each attraction ofrelay 3, but its delay is consequently greater thanthe duration of a closing impulsaso that relay 5 cannot fall backduring the transmission of a train of pulses. It only falls back when the operator of the calling station uses his dial for transmission of the next figure.

The circuit of the electromagnet of the entrance distributor X5 is closed as follows:

Ground, t ll, 255i, sector 1 of X5, the winding of X5 and thebattery.

The electromagnet X5 attracts its armature and remains inthis position till the release of relay 5 which takes place at the end. of the re-- ceptionof the train of pulses which represent the figure to be received, in this case the figure 2. I l

The circuit of the numerical element; corresponding to tens of thousands is close d a s follows: i

Ground, 254i, 132, wiper a of distributor X5 in A position 1, wire I, the winding of switch XI and merical element XI performs as many steps as 'tiine, exhausts its period of delay there are unities in the retransmitted figure.

In'theexample chosen the numerical element XI makes two steps and brings its wipers into position 2.

Relay 5, which is short-circuited for a long and is de-energized, thereby opening at tEI the attraction circuit of the entrance distributor X5 which releases its armature and brings its wipers into position 2; this disconnects the numerical element X2 correspondin to thousands.

The second figure is received by X2 in a manner identical to that described for the reception of the first figure.

The same applies to the third and fourth figures which are received by numerical elements "X3 and X4. The entrance distributor X5 after having effected distribution or" the four first figures to the numerical elements XI-X2-X3 X4 brings its wipers into contact with sectors b--d-cg and. iby means of the following connections: Ground, positions 5- 6'7-8 9 and 10 of sector a, the circuit breaker, the winding of XI and the battery.

In this position switch X5 receives the. pulses which determine the unit figure by means of the ,following connections:

Ground, 2541', 1'32, t52,'the winding of X5 and the battery, and brings thev wipers into a position determined by the number of the received impulses (in the example chosen, the figure 1).

After transmission of the last figure. the numerical elements of the recorder are in the following positions:

XI in position 2. X2 in position 5. X3 in position 8. X4 in position 8. X5 in position 1.

At the end of the selection the operator of the calling station receives the signal of the required station if the latter has been found free, or the engaged signal if the latter is busy, or the indicative signal of the overflow equipment. 7

On the other hand, the pulses received by the recorder must also be transmitted to the recorder for charged communications which causes the electromagnets of the printing recorder to take a. position corresponding to the number of the desired station.

Relay3 of the recorder (Fig. 4) i e-transmits the impulses which it receives from the calling station via:

Ground, MI, 732, contact I of the bank of the finder CE (Fig. '7), wiper I, contact b of mixer XI in position 4, the winding of relay I3 and the 7 battery.

The first attraction of the relay I3 sets relay I4 to work via:

Ground, tI3I, the inductive winding, the re- I sistance wound on relay I4 and the battery.

Relay I4 closes the holding circuit as follows: Ground, tI42, its two windings in series and the battery.

Relay I4 is short-circuited each time relay I3 1 is closed via:

Ground, tI lI, contact a of mixer XI in position 4, the winding of XI and the battery.

The electromagnet XI attracts its armature and remains in this position till the release of relay I4 which takes place at the end of the reception of the train of pulses which represents the figure to be received (here the figure 2).

The circuit of the element which prints the figure of the tens of thousands is closed as follows:

(Fig. 7) ground, tI32, contact a of mixer XI in position 4, wirev I, point II (Fig. 8)v the winding of the electromagnet 3 and the battery.

At each emission of negative current by the dial of. the calling station relay 3 of the recorder (Fig. 4) is released, and accordingly relay I3 of the recorder for charged communications is attracted; on the hand, relay 3 of the recorder is attracted at each emission of positive current which in turn releases relay I3 of the recorder for charged communications.

The circuit of the printing element 3 for the figure representing tens of thousands (Fig. 8) is, therefore, established at each emission of It falls back only when the opnegative current and ceases at each emission. of positive current. It follows from that. the print- .ing element 3 makes as many steps as there are units in the transmitted figure.

In the example chosen the printing element 3' brings the figure 2 of its wheel which is provided with printing characters, opposite the paper band.

Relay I4 of the recorder for charged communications (Fig. 7) is then short-circuitedby the contact rI3I for a long time, and exhausts its period of delay and falls back, thereby openingat tI4I the attraction circuit of the electromagnetof mixer XI which releases its armature and brings its wipers into position 5, thus disconnecting the printing element 3 and connecting the'printing element 4 for the figure which represents thousands. I

Contact 133 of. electromagnet 3 (Fig- 8) is opened. mechanically as soon as the electromagnethas left its rest position. On the other hand contact t32 is also established mechanically, but only when the electromagnet has left its rest position, and only till its return into this position.

The second figure is received on the printing electromagnet 4 in a manner identical to that described for the first figure, mixer XI of the recorder for charged communications (Fig. 7) being in position 5 instead of 4. 1

The third, fourth and fifth figures are received by printing elements 5-6-1 (Fig. 8) mixer XI of the recorder for charged communications successively occupying the positions 6, 7, 8.

After the reception of the last figure the printing elements of the printing recorder are in the following positions:

3 in position 2. 4 in position 5. 5 in position 8. 6 in position 8. I in position 1.

After the reception of the last figure mixer XI of the recorder for charged communications (Fig. 7) passes into position 9, the attraction circuit of its electromagnet being open at tI I I.

In this position, printing of the number of the called station is effected.

Type wheels carrying printing characters are shown at III, H2, H3, II4,1I5,1I6,1I1. Holding contacts which are mechanically held in their position are shown at 32, 42, s2, 62, 1'2, 92, 33, 43, 53, 63-, I3, 93.

The circuit of the electro-hammer of the printing recorder is closed as follows:

Ground, 7584 (Fig. 7), contact a in position 9 of mixer XI, wiper IN of finder CE, contact IN (Fig. 8), the winding of the electromagnet 8 and. the battery.

The electromagnet 3 attracts its armature and presses the paper band against the wheels of the printing electromagnets 34--5-3-1 which are equipped with printing characters.

Now the circuit of relay I2 of the recorder for charged communications (Fig. 7) is closed as follows:

Ground, t8I, contact b of the mixer in position 9, the winding ofrelay I2, the resistance and the battery.

Relay I2 attracts tis armature and at tIZI, it closes the crossing circuit of the electromagnet of mixer XI as follows:

Ground, tIZI, contact 11- of mixer XI in position 9, the circuit-breaker, the winding of XI and the battery.

Mixer XI then brings its wipers into position 10, thereby interrupting, at 9, the circuit of the electro-hammer 9 of the printing recorder, which releases its armature.

In position 10 the circuit of the electromagnet for advancing the paper band is closed as fol lows:

Ground, t84, contact a in position 10 of mixer XI, wiper Ab of finder CEI, contact Ab (Fig. 8), the winding of the electromagnet I3 and the battery.

Electromagnet I3 attracts its armature and advances the paper band. By its contact tI3I it closes the circuit of the relay 2;

Ground, tI3I, the winding of 2 and the battery.

Relay 2 closes a holding circuit as follows:

Ground, t2'I, the winding of 2 and the battery.

Relay 2 then establishes a circuit for the return to rest of printing elements 3-456--I-- via:

Ground, t22, T32, r3I, the winding of 3 and the battery.

Ground, i23, T42, MI, the winding of I and the battery.

Ground, 1524, T52, Till, the winding of 5 and the battery.

Ground, 1525, T62, Til, the winding of 5 and the battery.

Ground, 2526, T12, 1'', the winding of I and the battery.

The vibrating elements now return to their rest position; in this position, contacts 2532, 2342, 1352, 1562 and 1572 are open, and contacts r33, r43, r53, r63 and T73 are closed. When all the printing elements have returned to their rest positions, relay 2 is short-circuited by means of the following connections:

Ground, T21, r33, r43, r53, r63, r13, T93 and the winding of relay 2.

Then relay 2 falls back, and all the printing elements are ready to receive the number of the calling station.

It has been mentioned above that the wipers of electromagnet XI of the mixer have been brought to position 10. In this position, relay I2 is short-circuited by the following circuit:

Ground, t8l, tI22, contact b of mixer XI in position 10 and relay I2.

Relay I2 then exhausts its period of delay and falls back thereby re-establishing its contact rI2I.

The circuit of relay 9 is similarly closed in this position as follows:

Ground, r84, contact 03 of XI, in position 10, the upper winding of 9 and the battery.

Relay 9 closes a holding circuit as follows:

Ground, t84, t92, the lower winding of relay 9, wiper IP of the finder CEI, contact IP (Fig. 8), the winding of the printing electromagnet for po ition 10 and the battery.

The electromagnet I 6 cannot start working because the resistance of the winding of relay 9 of the recorder for charged communications is too high to permit of its functioning.

The circuit of the combiner XI is closed as follows:

Ground, rI2 I, contact 0 of mixer XI in position 10, the circuit-breaker, the winding of XI and the battery.

Electromagnet XI position 11.

The recorder for charged communications then then brings its wipers into 18 begins the search for the calling station. The first phase consists in the search for the call finder which is in engagement with the calling line. As the designation of this call finder it is suificient to indicate the element representing hundreds to which this call finder is connected. The rotation circuit of finder RC of the recorder for charged communications is closed as follows:

The battery, 1123, TI I I, rIIII, contact 72 in position 11 of mixer XI, the circuit-breaker and the winding of the electromagnet RC to ground.

The finder RC begins to rotate automatically, and searches for the test plug to which a wire SC to which a wire SC, peculiar to each finder, is connected and which indicates to it that the wiper of the connection circuit is in engagement with the recorder.

The rotation circuit of electromagnet RC is opened as soon as wiper B of switch RC has reached this test plug. Then relay II of the recorder for charged communications (Fig. 7) begins to operate by means of the following connections:

(Fig. 6), the secondary of the transformer, rectifier RDI or RD2 in the same direction as the current, point 23 (Fig. 4), H2, rIII, wiper SI of the finder of the recorder, contact SI of the bank (Fig. 3), the wiper and bank S of the finder of the connection circuit, wire Sc (Fig. 7), the bank and wiper b of finder RC, contact J of mixer XI in position 11, tI05, the winding of relay I I, H24, tI3, wiper S of the finder of recorder CE, the bank S (Fig. 4), tIIG, rectifier RDI in the same direction as the current, t'I2, point 24 (Fig. 6), rectifiers RD3 or RD4 in the same direction as the current, and the secondary of transformer TFI.

Relay II opens the rotation circuit of finder CE at H l I. At tI I2, it closes the attraction circuit of relay I2 by means of the following connections:

Ground, t8l, tII2, contact b of the mixer in position 11, the winding of relay I I, the resistance and the battery.

Relay I2 closes a holding circuit by means of contact TI22. It also closes the circuit of the electromagnet of mixer XI by means of the following connections:

Ground, tI2I, contact 12 in position 11. of XI, the circuit-breaker, the winding of XI and the battery.

The electromagnet of XI into position 12.

Relay I2 is then short-circuited by contact b of mixer XI in position 12, and falls back.

Relay II, the circuit of which is open (at contact III of the mixer XI), falls back in its turn.

The rotation circuit of finder RA is then closed via:

The battery, 11 I I, tIUI, contact h of mixer XI in position 12, the wiper and bank 0 of finder RC, the circuit-breaker, the winding of RA, and the battery.

The finder RA begins to rotate automatically and searches for the test-plug to which a wire Sa peculiar to each subscriber is connected, and which indicates to it that wiper S of the connection circuit is in engagement with the recorder and that wiper S of the call finder is in engagement with the calling line. The rotation circuit of the electromagnet RA is opened as soon as wiper a (or b, c, d, e, or f according to the element representing the hundred to which the subscriber belongs) reaches this test-plug. The circuit of then brings its wipers 

